In bowl of stand mixer fitted with paddle attachment, and with mixer speed set to medium-high, cream the butter, until smooth and creamy, stopping as necessary to scrape sides of bowl. With mixer set on slow speed, add the icing sugar, ¼ cup at a time. Increase mixer speed to medium-high when all of the icing sugar has been added and cream the sugar well with the butter, for about 2-3 minutes. Beat in vanilla.
Yield: Apx. 13-14 double/paired cookies (depending on amount of dough used per cookie)